40l. mauve on blue in pair canc. "1" (=ΑΘΗΝΑΙ). Right stamp with double control number, distance 0.5mm horizontally and 1mm vertically (Kound. 32.1.a) while left stamp with normal control number!!! Very large/even margins all but light yellow toning. A UNIQUE CONTROL NUMBER ERROR CASE SO FAR. (Hellas 20Ib+20IbNoI).